The state-run Defense Acquisition Program Administration instructed two companies not to ship tear gas to the Gulf state after they inquired about possible exports, agency officials said.

The two companies exported tear gas to Bahrain in 2011 and 2012, the officials said. Exports of tear gas need government approval because a key ingredient is listed as a strategic material in South Korea, they said.

The officials, who spoke on condition of anonymity because of department rules, said the decision was made in consideration of the overall situation in Bahrain, including media reports that misuse of tear gas had caused the deaths and injuries of protesters, and calls by rights groups for a ban on exports of the crowd control material to the country.

International rights group Amnesty International hailed South Korea’s decision. “The South Korean authorities should be commended for this move to help prevent further human rights violations in Bahrain,” Brian Wood, head of arms control and human rights at the group, said in a statement.

Bahrain’s interior ministry said in a statement Wednesday that it had not been formally informed of any ban on the export of tear gas to the island kingdom.

The ministry defended its use of tear gas as in compliance with international law, and made a point of distinguishing the use of tear gas in “riot control situations” rather than in sanctioned gatherings and demonstrations.

“Tear gas is used by Bahrain’s police force only as a necessary and proportionate measure and in public order and riot control situations,” the ministry said. It added that legal and disciplinary action is taken whenever its police officers breach its code of conduct.

Bahrain, a Sunni-ruled nation, has faced continuing unrest since the country’s Shiite majority began protests against the government in early 2011. Bahraini Shiites are demanding more rights from the Sunni rulers.